package model;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

//实现博客的基本操作，目前只实现增删查
public class BlogDao {
    // 1. 往博客表里, 插入一个博客
    public void insert(Blog blog){
        Connection connection=null;
        PreparedStatement statement=null;
        try {
            // 1) 和数据库建立连接
            connection=DBUtil.getConnection();
            // 2) 构造 SQL 语句
            String sql="insert into blog values(null,?,?,?,now())";
            statement=connection.prepareStatement(sql);
            statement.setString(1,blog.getTitle());
            statement.setString(1, blog.getTitle());
            statement.setString(2, blog.getContent());
            statement.setInt(3, blog.getUserId());
            // 3) 执行 SQL
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            // 4) 关闭连接, 释放资源
            DBUtil.close(connection, statement, null);
        }
    }

    // 2. 能够获取到博客表中的所有博客的信息,太长的就只显示部分信息（需要截断）
    public List<Blog> selectAll(){
        List<Blog> blogs=new ArrayList<>();
        Connection connection=null;
        PreparedStatement statement=null;
        ResultSet resultSet=null;
        try {
            connection=DBUtil.getConnection();
            //这里按时间降序返回
            String sql="select * from blog order by postTime desc";
            statement=connection.prepareStatement(sql);
            resultSet=statement.executeQuery();
            while (resultSet.next()){
                Blog blog=new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                String content=resultSet.getString("content");
                // 这里需要针对内容进行截断(太长了, 就去掉后面)
                if(content.length()>50){
                    content=content.substring(0,50)+"……";
                }
                blog.setContent(content);
                blog.setUserId(resultSet.getShort("userId"));
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                blogs.add(blog);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,resultSet);
        }
        return blogs;
    }

    // 3. 能够根据博客 id 获取到指定的博客内容 (用于在博客详情页，不需要截断)
    public Blog selectOne(int blogId){
        Connection connection=null;
        PreparedStatement statement=null;
        ResultSet resultSet=null;

        try {
            connection=DBUtil.getConnection();
            String sql="select * from blog where blogId=?";
            statement= connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            resultSet=statement.executeQuery();
            // 此处我们是使用主键来作为查询条件的. 查询结果, 要么是1, 要么是0
            if(resultSet.next()){
                Blog blog=new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                blog.setContent(resultSet.getString("content"));
                blog.setUserId(resultSet.getShort("userId"));
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                return blog;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(connection,statement,resultSet);
        }
        return null;//如果查询不到返回null
    }

    // 4. 从博客表中, 根据博客 id 删除博客.
    public void delete(int blogId){
        Connection connection = null;
        PreparedStatement statement = null;

        try {
            connection= DBUtil.getConnection();
            String sql="delete from blog where blogId=?";
            statement=connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(connection, statement, null);
        }
    }
}
